<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
	<script type="text/javascript">
		var  result=confirm("下一届奥运会举办地点？");
		if (result) {
			alert("a.北京")
		}else if()
	</script>
	</body>
</html>
